The invention concerns a device, circuit and method for controlling the impulses generated by the discharge of a capacitor placed either in series or in parallel with the load and, in the case of a parallel connection, having no more than one electronic switch. The invention further concerns a novel switching tube for use as such switch and having other uses and equipped with at least one important further device or circuit.
The invention is intended above all for application to electronic flashes, stroboscopes and lasers.
Such devices are now only known for effecting such control in an automatic manner and with the capacitor causing the impulse to bypass the load. Apparatus of such kind is disclosed in U.S. Pat. No. 3,033,988 and is composed of a device which controls the light of a photographic enlarger and in which a gas-discharge switching triode with an external firing electrode or a mercury tube is provided as a second switch, always with an impedance of about 0.1 ohm. Concerning the light sensor of this patent, U.S. Pat. No. 3,350,604 states, at column 3, lines 27-32: "In order to achieve the high photocell dark impedance with the required high light sensitivity, the light sensitive element must be a photomultiplier tube. Such tubes require a rather complex power supply. This results in a package which is sufficiently bulky as to preclude its use in portable, camera mounted flash equipment." Another known device of the same kind is disclosed in U.S. Pat. No. 3,350,604, which is essentially based on the disclosure of U.S. Pat. No. 3,033,988, and represents a modification thereof in that this device makes use of a nonreactive light integrator, i.e. one without a capacitor, and the patent states that the use of this is more advantageous than that of the integrator of U.S. Pat. No. 3,033,988.
These known devices, which can only operate in an automatic manner, i.e. by being coupled permanently to a sensor, always have two or more switches. The switch of the second patent (U.S. Pat. No. 3,350,604) is a xenon gas-filled discharge tube, a variant of the well-known xenon gas-filled photoflash tube, equipped with an internal firing electrode and having a pressure of about 100 mm Hg. The internal resistance of this tube is mentioned as being 0.1 ohm.